I've tried as hard as I can to caution Cubs fans that, as good a team as the organization assembled, the odds are technically against them; at WBEZ, Chris Hagan put together a neat simulator to get across that concept. All the little happenstances that would be merely novel during the regular season can end a great team's shot at a title.

The Cubs' modestly nerve-wracking 3-1 victory over the Giants is a good example of the fickleness of the game. The Giants' best hitter that night was Conor Gillaspie, whom Chicagoans will remember hitting .237/.276/.364 for the White Sox in 2015 as a well-below-replacement third baseman. After giving the Giants a mere 101 at-bats this year, Gillaspie put up 13 total bases in the playoffs, third overall, as of today, behind Toronto stars Edwin Encarnacion and Josh Donaldson. Other examples of unpredictable game-changers: Jake Arrieta, a good hitter as pitchers go, staked the Cubs to a three-run lead with a home run in Game 3, giving him as many RBI on the series as slugger Kris Bryant. And Giants pitcher Matt Moore, an abysmal hitter, gave his team an early lead last night.

But the way the series ended reflected the two teams' strengths and weaknesses during the season, and how their front offices addressed them (or didn't).

The Giants got eight great innings out of Moore, a clever deadline acquisition on an affordable contract who gave them a fourth starter nearly as good as the Cubs' Lackey. With a 5-2 lead, they turned Moore's work, and the potential to push the series to a winner-take-all Game 5, over to their mess of a bullpen.

Fangraphs publishes a handy rundown of each team's bullpen throughout the season so that fantasy baseball players can find the closer within volatile situations. At the end of the season, the Giants were on red alert (emphasis mine):

[Closer Santiago] Casilla hasn’t been really that different of a pitcher in 2016 than his last couple seasons (outside of luck-based factors controlling his ERA). That said, relief leverage (especially in September) is a “what have you done for me lately?" kind of thing, and Casilla’s ERA over the last month is ~8.00. With no [relief pitcher] pitching exceptionally well in this bullpen, it’s a bit of a dice roll to who is up next. Sergio Romo has the pedigree and a decent ERA over the last month, but he’s walking too many guys. Hunter Strickland is somewhat the opposite — unproven, decent peripherals, but bad performances lately. Derek Law and Will Smith might get the next shot (depending on handedness) but only Bruce Bochy knows. I’d stay away from here unless desperate.

Bochy managed to replace Moore with Law, Romo, Smith, Strickland, and Javier Lopez, who had a not-great 4.05 ERA and a terrible 1.46 WHIP on the season. All in the same inning.

In the first half of 2016, both the Cubs and Giants had good teams with mediocre bullpens. By Fangraphs' WAR, the Cubs' bullpen ranked 24th, the Giants ranked 26th. So both teams paid big for help: the Cubs acquired Aroldis Chapman, the best closer in baseball, and the Giants acquired Will Smith, who despite his anonymity in Milwaukee was one of the best setup men in baseball. But as Dave Cameron points out, "the way Smith was used the last few months has just been weird. The team paid a high price to get a good reliever to upgrade their bullpen, and despite a total implosion from the internal options, Bochy kept going to just about anyone besides the good reliever the team traded for, even as the good reliever pitched really well."

In the second half of the season, the Cubs' bullpen improved to eighth-best; the Giants, just 17th. Chapman pitched in all four games in the series, saving three games, one of nine players to have saved every win of a divisional playoff. Despite his one blown save, over the 3.1 innings Chapman pitched he was more or less the Chapman you'd expect: three hits, one walk, seven strikeouts, one earned run.

Aroldis Chapman came at a big price for the Cubs, and unlike Smith, he's a free agent after this season. He's the most unpredictable and hardest to judge of acquisitions, a win-now closer who could be either critical or completely irrelevant based on circumstances outside his control, or the front office's. He's an insurance policy, and one that almost immediately paid out.